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c190c3b16c
The synchronize_sched_expedited() currently invokes try_stop_cpus(), which schedules the stopper kthreads on each online non-idle CPU, and waits until all those kthreads are running before letting any of them stop. This is disastrous for real-time workloads, which get hit with a preemption that is as long as the longest scheduling latency on any CPU, including any non-realtime housekeeping CPUs. This commit therefore switches to using stop_one_cpu() on each CPU in turn. This avoids inflicting the worst-case scheduling latency on the worst-case CPU onto all other CPUs, and also simplifies the code a little bit. Follow-up commits will simplify the counter-snapshotting algorithm and convert a number of the counters that are now protected by the new ->expedited_mutex to non-atomic. Signed-off-by: Peter Zijlstra <peterz@infradead.org> [ paulmck: Kept stop_one_cpu(), dropped disabling of "guardrails". ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> |
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| tiny.c | ||
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| tree.c | ||
| tree.h | ||
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| update.c | ||